Egyptian authorities arrested nine suspected militants in the volatile Sinai Peninsula on Wednesday, state news agency MENA said, as troops press ahead with an extensive campaign to crush an Islamist insurrection in the region.

Forty-three shacks and buildings allegedly used as bases for terrorist attacks were destroyed in the raids that targeted the southern part of the North Sinai city of Rafah.

The extensive offensive in the underdeveloped, desert region involves the destruction of a network of smuggling tunnels connecting Sinai with the Palestinian Gaza Strip.

Security sources told MENA that two more passages were destroyed on Wednesday, adding to the overall 1,639 tunnels the army said, earlier this week, that it had already eliminated.

Since the ouster of Islamist president Mohamed Morsi last summer and an ensuing crackdown on his supporters, Egypt has been hit by an upsurge in Islamist militancy, led by Sinai-based groups, mostly targeting security forces.

More than 500 policemen and conscripts have since been killed, while militant attacks have gradually extended to the capital Cairo and the Nile Delta.

A soldier was killed in a firefight on Tuesday in North Sinai’s Rafah, and a nine-year-old girl was killed on Monday when a rocket landed outside her home in the same governorate’s Sheikh Zuweid city.

Two days earlier, four children were killed in the North Sinai town of Al-Jour when a mortar round was fired at their home. Both attacks were believed to have targeted soldiers.